Do Sonograms Cause Autism? A New Study

A new paper (“Are Prenatal Ultrasound Scans Associated with the Autism Phenotype? Follow-up of a Randomised Controlled Trial” by Yonit K. Stoch, Cori J. Williams, Joanna Granich, Anna M. Hunt, Lou I. Landau, John P. Newnham and Andrew J. O. Whitehouse) takes another look at the results of a randomized trial started in 1989. Half the mothers were given one ultrasound during their pregnancy, the rest got five. This study gave a questionnaire sensitive to autism-like traits to the now-grown-up children. This is potentially more sensitive than binary (yes/no) assessment because the questionnaire has about 50 questions.

Here is the entire abstract:

An existing randomised controlled trial was used to investigate whether multiple ultrasound scans may be associated with the autism phenotype. From 2,834 single pregnancies, 1,415 were selected at random to receive ultrasound imaging and continuous wave Doppler flow studies at five points throughout pregnancy (Intensive) and 1,419 to receive a single imaging scan at 18 weeks (Regular), with further scans only as indicated on clinical grounds. There was no significant difference in the rate of Autism Spectrum Disorder between the Regular (9/1,125, 0.8 %) and Intensive (7/1,167, 0.6 %) groups, nor a difference between groups in the level of autistic-like traits in early adulthood. There is no clear link between the frequency and timing of prenatal ultrasound scans and the autism phenotype.

Parrish Hirasaki pointed out to me that when the study was done the intensity of ultrasounds was eight-fold less than now. Here’s what the paper says about this:

Technological advancements over the past two decades have led to considerable improvements in ultrasonographic capabilities, with corresponding increases in acoustic output.

Did you read that and realize the intensities have increased by a factor of eight? Neither did I. Such a big difference in intensity means the results are not serious evidence — contrary to what the abstract implies — against the idea that sonograms are now causing autism.

More Asked about the failure to make clear the difference in intensity, the corresponding author, Andrew Whitehouse, replied:

The parameters of the ultrasound scans were reported clearly in the Methods section, and we refer to several other articles that include a description of the USS administered in this cohort. We are also very clear in the Discussion when we state that “the current study was not designed to investigate the use of [modern] instruments”.

I disagree. So what if the parameters of the ultrasound scans were reported clearly in the Methods section? That’s not the issue. The issue is failure to make clear the huge intensity difference between the ultrasounds they studied and modern ultrasounds. Saying that “the current study was not designed to investigate the use of [modern] instruments” does not make clear at all (much less “very clear”) how much modern ultrasounds differ from the ultrasounds actually studied. Any study can put caveats like that at the end. Yet few studies are as irrelevant as this one to the question they claim (in the title, abstract and introduction) to help answer.

Do Sonograms Cause Autism? New Evidence

A female American engineer named Parrish Hirasaki has started a website devoted to the idea that prenatal ultrasound is a major cause of autism. It includes a long list of supporting research. In spite of all this research, “as of spring 2011, analyzing the ultrasound results was not among the 23 hypotheses [about the cause of autism] being tested by the National Children’s Survey”, says the website.

I first heard this idea from Caroline Rodgers, a science writer, and have blogged about it several times. Nevertheless, the website’s home page taught me several things I didn’t know:

1. “A recent major study of twins supports earlier studies in concluding that environmental exposures during or shortly after gestation cause a majority of autism cases.” This is inconsistent with many other explanations (e.g., vaccine, genetic).

2. “In a recent study, autistic children had reduced connectivity between the two sides of the brain.” Which supports the idea that neural misdevelopment is a cause of autism.

3. “Twenty years ago, the FDA increased the allowable intensity of prenatal ultrasound 8-fold to improve images. Autism rates have risen dramatically since that time.”

4. There is “widespread misunderstanding among ultrasound operators of the safety guidelines.”

5. “A fast-growing commercial business is keepsake ultrasound photos. Franchisers advertise that no medical background or certification is required.”

I asked Hirasaki a few questions.

How did you become interested in this?

My age and my profession led me to the theory that the rise in autism is caused by exposure to prenatal/neonatal ultrasound.
  1. When my last child was born in 1978, there was one ultrasound machine serving the entire population of Houston.
  2. My work experience in the industrial and aerospace industries was extensive in heat and vibration.
  3. For several decades, my work included industrial instrumentation in chemical plants and refineries. Most such instruments require routine calibration to stay accurate.
  4. In the space program, there are always redundant devices because mechanical and electrical equipment may malfunction.
  5. A first cousin died at age 6 of cancer caused by x-ray overdose in the 1940’s. I am old enough to remember getting my feet x-rayed at the shoe store.

Who else, in addition to Caroline Rodgers, has independently had this idea and written or posted about it?

Manuel Casanova, a neurologist. Nancy Evans, a science writer.

When you started looking into possible causes of autism, did you look into other possible explanations?

No. I asked myself what had changed about having a baby. Ultrasound seemed to be the obvious major change. Exposure to caffeine, smoking, alcohol and medications had all decreased.

Was there any particular evidence that you found especially persuasive?

On my website, there are 37 papers pertinent to the topic. My primary theory is that overexposure is the cause. The most persuasive evidence that points to this is:

  1. The girls in the Kaiser-Permanente study who have the highest exposure to ultrasound during the second trimester have more than double the expected rate of autism.
  2. Interruption of the neural migration patterns in the brains of the overexposed mice in the Yale study.
  3. A known cause of autism is the mother having an infection. One theory is that as the mother’s body fights the infection with a fever, the rise in temperature of the fetal brain causes the damage. The temperature rises in tissue exposed to ultrasound are reported in a paper which calls for the FDA to examine the current allowable limits.
  4. The much higher rate of autism for children who weighed less than 4.5 pounds at birth. The medical and AIUM protocol for infants this small is an immediate head ultrasound.
What has made it difficult for the research community to find this?
  1. The researchers have education and experience  [and funding — SR] in medicine, biology, genetics. This is where they look.
  2. In the 1950’s, the FDA turned the regulation of medical ultrasound over to the American Institute for Ultrasound in Medicine (AIUM) which is funded by the government and the manufacturers. In November 2011, I expressed my concerns via email to the AIUM Bioeffects Committee. The chair responded that the AIUM monitors the topic and has conducted a thorough search of existing literature (2008) and found no link except the “weak association” in the Kaiser-Permanente study. The report states that there are potential risks to administering ultrasound tests, which include “postnatal thermal effects, fetal thermal effects, postnatal mechanical effects, fetal mechanical effects, and bioeffects considerations for ultrasound contrast agents.” Another section says “the long-term effects of tissue heating and cavitation have shown decreases in the size of red blood cells in cattle when exposed to intensities higher than diagnostic levels. However, long-term effects due to ultrasound exposure at diagnostic intensity is still unknown.” In 1992, the AIUM and the FDA increased the allowable intensity of prenatal ultrasound 8-fold without knowing whether it was safe. Twenty years later, they still don’t know.
  3. Engineers who could do such research receive funding from the manufacturers. Such a researcher would be unlikely to propose research that could decimate the industry.
  4. This is the classic search for a needle in a haystack. Less than 1 in 300 ultrasounds is causing noticeable brain damage.

I would add that links between sonograms and left-handedness are more evidence that sonograms can cause important brain changes. Here is a doctor who does sonograms dismissing the connection but what I find important is that the connection has been found repeatedly.

High Defect Rate in Ultrasound Machines That Scan Pregnant Women

Two studies in Sweden by the same group have found high rates of defects in ultrasound machines used to scan pregnant women. The line of research began when doctors at the Karolinska Hospital discovered that many of their ultrasound machines were malfunctioning. Continue reading “High Defect Rate in Ultrasound Machines That Scan Pregnant Women”

New Support for Prenatal Ultrasound Cause of Autism

I have blogged several times about Caroline Rodger’s idea that sonograms during pregnancy greatly increase the risk of autism in the fetus. Her idea is supported by several lines of evidence, as she explains in this talk.

A new study provides more evidence. It found a high concordance rate among fraternal twins. In the general population from which the new study was drawn (California), about 1 child in 100 has autism. But if you are an identical twin, and your co-twin has autism spectrum disorder, your chance of having the same diagnosis is about 70%. The crucial point of the study is that the concordance was also high for fraternal twins: about 40%.  As one commenter put it, this result “puts a spotlight on pregnancy as a time when environmental factors might exert their effects”.

Another study found more risk of autism if the mom took an anti-depressant during pregnancy. This supports the idea that a bad prenatal environment causes autism.

Thanks to Paul Sas and Gary Wolf.

PFCs, Ultrasound, and Autism

Robert Delaney is a geologist who does environmental cleanup in Michigan. While cleaning up an abandoned military base, he found remarkably high contamination by a chemical called PFOS. He had been wondering what causes autism. He came across a rodent study that found that the combination of PFOS and ultrasound was much more damaging to the nervous system than either alone. (See also this study.) He remembered that study when he read my posts about ultrasound and autism. He wrote to me: Continue reading “PFCs, Ultrasound, and Autism”

Prenatal Ultrasound and Autism: Multiple Voices

I previously blogged (also here) about Carolyn Rodgers’s idea that prenatal ultrasound may cause autism. It turns out that she isn’t the only person with this idea; researchers at the University of Louisville recently published the same idea.

I learned about the Louisville study from Anne Weiss, who said the connection has been plausible for a long time.

Ultrasound was introduced into obstetrics in the 1970’s and was generally restricted to high-risk pregnancies.  By the 1980’s policy statements were issued by ACOG, the NIH and equivalent bodies in Europe and Canada stating that its use should remain limited to high-risk cases. Despite these recommendations, ultrasound technology became common in hospitals and doctors’ offices and routinely applied to low-risk populations. Within a short time the majority of pregnant woman were being exposed at prenatal visits, during multiple scans in hospitals, and during continuous monitoring during labour (which could mean 12 to 14 hours during childbirth alone). Skills and techniques used to monitor the fetus prior to the introduction of ultrasound (in utero and during the birth process) were slowly undermined by the technology and often underutilized.  Iatrogenic effects from false positive readings, – unnecessary C- sections, inductions, instrumental deliveries etc. caused harm to moms and babies, especially in the early 1980’s.

Three important names in the 1980s were (1) Robin Mole, who presented a paper “Possible Hazards of Imaging and Doppler Ultrasound in Obstetrics” to the Royal Society of Medicine Forum on Maternity and the Newborn:  Ultrasonagraphy in Obstetrics, April 1985. She was former director of the Medical Research Council Radiobiology Unit, England.  Also the work of (2) M.E. Stratmeyer – Research in ultrasound.  A public health view.  Birth and Family Journal 1980 and (3) Doreen Liebeskind – still at Albert Enstein and a prof of radiology- presented at a symposium at Columbia in 1983.   She was concerned that ultrasound may be producing subtle changes in the fetal brain perhaps affecting behavioral mechanisms, possible changes in reflexes, IQ, attention span or some of the more subtle psychological, psychiatric or neurological phenomena.  Referred to animal and lab studies that showed ultrasound may cause chromosomal damage, breakdown of DNA, etc.  There are others who sounded the warning that this was not a benign technology but these voices were crowded out for varied reasons like threats of litigation, loss of the traditions skills of birthing etc.

There were also Japanese studies that raised concerns about ultrasound. Weiss continued:

Unfortunately the use of ultrasound in obstetrics has not declined, despite safety concerns and the lack of research to rule out serious neurological effects.  It’s so entrenched in modern obstetrical practice.    Doctors use the machines to protect themselves from litigation – in the case of fetal abnormalities, undetected multiples, placenta previa, neurological or physical damage to the fetus during childbirth, stillbirth etc.  It has almost become a form of entertainment – you can get photos and videos of baby’s ultrasound.  It’s disturbing how benign it appears.

Within the context of the work I do, ultrasound is just one of many concerns I have with the over-management and medicalization of childbirth.  My clients come to me to find ways to subvert this within the hospital setting or to prepare for a home birth with a midwife.   I also get referrals from doctors whose patients are dealing with difficult issues while pregnant.

Prenatal Ultrasound and Autism: Lack of Study

Caroline Rodgers, whose ideas I blogged about yesterday, wrote to me about lack of research on the possibility that prenatal ultrasound causes autism:

I have heard confidentially that applications for funding of prenatal ultrasound studies (not specifically investigating autism) have been repeatedly denied over the years — which helps explain the great paucity of safety studies, especially since the early ’90s, when the FDA approved an allowable eightfold increase in acoustic output. As recently as this year, funding was denied an ambitious, multi-site study that would have investigated if there was a relationship between ultrasound and autism.

In 2006 when Yale neuroscientist Pasko Rakic announced the results of his study that found prenatal ultrasound interrupted neuronal migration in mice in a way that was consistent with the brains of autopsied autistics, I was surprised that several scientists, including Rakic, did their best to downplay the results. At the time, Rakic was one of many of Autism Speaks’s scientific advisors.

I have spoken with various people throughout the NIH about my concerns [about ultrasound]. They all pointed to various large studies they believe are investigating ultrasound as a possible environmental cause of autism — most recently, the National Children’s Study and EARLI, but when I tracked down the study designs, it turned out that ultrasound is not being studied.

In a report at the time Rakic’s study was published, he indeed downplayed the results:

Dr. Pasko Rakic, chairman of the Yale department of neurobiology and leader of the study, was quick to offer parents reassurance about the safety of ultrasound — done for the proper reasons — in human pregnancies.

“If I had a daughter and she was pregnant, I would recommend she had it for medical reasons,” Rakic said.

Another researcher agreed:

“I couldn’t agree with him more,” said Dr. Joshua Copel, a professor of obstetrics, gynecology and reproductive sciences at Yale and spokesman for the American College of Obstetrics and Gynecology (ACOG). He was not involved in the study. . .

The researchers noted that mice are very different from humans, so the results of their study must be interpreted with caution.

“The forms of migration [of brain cells] and the timing of migration differ in primates like humans than in mice,” Copel said. “In humans, there is a much longer period in which neurons [nerve cells] are migrating.”

Does that sound “very different”?

Autism and Prenatal Ultrasound (more)

I blogged earlier about Caroline Rodgers’s idea that prenatal ultrasound may cause autism. She believes this idea isn’t getting the attention it deserves.

Recently she wrote to the head of Health and Human Services:

The latest autism prevalence figures released in December showed that while the overall autism rate increased more than 50% in the four years ending in 2006, there were significant differences across ethnic groups. White women had a much higher incidence of autism among their children than Black or Hispanic women. White mothers had 9.9 autistic children per 1,000, versus Black mothers who had 7.2 and Hispanic mothers who had 5.9.

There were also geographic differences. Among the 10 states with monitored sites, Alabama and Florida had the lowest autism rates, with averages of 4.2 and 4.6 per 1,000, respectively – far lower than the two states with the highest autism rates, Arizona and Missouri, which tied at 12.1 per 1,000. One interesting apparent statistical anomaly occurred among Alabama’s Hispanic population, which had a 68% decrease in autism while the overall national increase was 57%. In trying to understand why Alabama Hispanics had such a decrease in autism, I searched for evidence of public health policy changes. What I found was a surprise: according to a CDC multi-state surveillance report, Alabama and Florida were two of three states that had cutbacks in Medicaid funding for prenatal care during the time mothers in the study were pregnant. (The third state, West Virginia, was not among those monitored for autism in the latest study.)

Digging deeper, I turned up a CDC report on the timing of entry into prenatal care. The report showed that although most women started prenatal care in the first trimester, the percentages of both Black and Hispanic women who lacked early (first trimester) prenatal care were nearly twice that of White women . . . Over the span of the 10-year study, more women [in] all ethnic groups received early prenatal care, but the 2-to-1 ratio remained the same. . . .
Taken together, these three CDC reports tell a disturbing story: as more women . . .  received more early prenatal care, the autism rate among their children increased, with those women receiving the most early prenatal care having the highest percentage of autistic children. . . .

A rigorous UC Davis study, published in January, of California children born between 1996 and 2000 identified 10 autism clusters . . . Highly educated women were much more likely to have children diagnosed with autism than parents who did not finish high school. In six of the clusters, the rate was as high as 4 to 1. Returning to the CDC Entry into Prenatal Care report, it is striking to note that in 1997 only 8.5% of pregnant women with some college education had delayed prenatal care, versus 29.9% of women who were not high school graduates – further [linking] early prenatal care [and] autism.

A study published in November on prenatal ultrasound trends from 1995-2006 found that the odds of a woman receiving an ultrasound during a prenatal visit nearly doubled over [those] 10 years. . . . The geographical and ethnic differences . . . dovetail with many of the geographical and ethnic differences found in the latest autism prevalence report. For instance, Southern women were 40% less likely to receive an ultrasound during a prenatal visit than Northeastern women, which could help explain why Florida and Alabama had the lowest autism rates among the states monitored. Also, Hispanics, who had the lowest overall autism prevalence rates in both the 2004 and 2006 CDC reports, were 20% less likely to receive an ultrasound during a prenatal than White women.

Not all the statistics available in these reports support the idea that prenatal ultrasound is causing autism. For instance, Southern states such as Georgia and North Carolina did not have low autism rates, but [perhaps this is because] the ultrasound trends study did not take into account “keepsake” ultrasound . . .

She also notes that a study by Yale neuroscientist Pasko Rakic “found that prenatal ultrasound disturbed neuronal migration in mice.”

Here is the broad argument. 1. Autism is correlated with wealth. It is absurd that autism causes wealth; it is unlikely that both are caused by something else. Thus this correlation makes it plausible that autism is caused by something that rich people have more of than poor people. Obviously rich people have more prenatal ultrasound. 2. A localized decrease in autism happened at the same time autism almost everywhere was increasing. At the same place and time prenatal ultrasound screening surely declined. This correlation is very difficult to explain with other ideas about what causes autism. Dozens of things (e.g., genes, diagnostic criteria) previously proposed as explanations of autism remained roughly constant at the same time as the decrease. 3. The mice data make the linkage considerably more plausible, assuming (a) the ultrasound dosage was reasonable and (b) humans with autism have unusual neural wiring that resembles the changes seen in the mice.

The full letter is on her blog. An article by Rodgers about this

Does Prenatal Ultrasound Cause Autism?

Caroline Rodgers, a science writer, has noticed some very interesting correlations:

The new autism figures published in the CDC’s 12-18-09 Morbidity and Mortality Weekly Report (MMWR) reveal an apparent anomaly: While there was an overall average autism increase of 57 percent in children born between 2002 and 2006, Hispanics in Alabama showed a 67 percent decrease in autism.

The mothers of the first batch of children who were eight years old in 2002 would have been pregnant in 1993. Therefore, I looked at what changes might have occurred in Alabama’s public health policy in 1993 that would explain a 67 percent drop in the autism rate of Hispanic children born between 2002 and 2006.

According to the 2002 PRAMS Surveillance Report: Multistate Exhibits Medicaid Coverage for Prenatal Care .

During 1993-2002, the prevalence of Medicaid coverage for prenatal care . . . decreased in 3 states (Alabama, Florida and West Virginia).

This particular correlation is in addition to a broad correlation between wealth and autism (more wealth, more autism):

Also significant in last week’s MMWR report were the ethnic differences in autism prevalence found among non-Hispanic whites, blacks and Hispanics. The autism rate in the monitored areas throughout the United States of children of non-Hispanic white women was 102 per 10,000; among black children, 76 per 10,000; and among Hispanic children, 61 per 10,000 – roughly half of the non-Hispanic white rate. These results seem counter-intuitive, since the non-Hispanic white population could be expected to have more access to prenatal care than the black or Hispanic populations. Yet if autism risk is increased by exposure to prenatal ultrasound, these figures make perfect sense.

This isn’t cherry-picking. Rodgers believed that we should take seriously the idea of a prenatal-ultrasound/autism link based on entirely different data.